Tuesday, May 14, 2013

AVO Reports Possible Eruption From Pavlof Volcano [UPDATED 6/10]

Pavlof volcano on the Aleutian Peninsula of Alaska has entered an eruptive phase after increased seismicity and thermal anomalies detected in satellite data. A Facebook post from USGS issued the following statement today (although a bit late).

"On May 13, 2013, USGS-AVO reported that seismic activity at Pavlof increased that morning, along with the presence of an intense thermal anomaly at its summit. The Alert Level is "Watch;" Aviation Color Code Orange.

Similar patterns of seismicity and elevated surface temperatures have previously signaled the onset of eruptive activity at Pavlof. Although not yet visually confirmed, a low-level eruption of lava has likely begun from a summit vent. No ash clouds have been detected."

An overflight by a pilot has confirmed the presence of a summit spatter cone, and advancing lava flow. (seen below in a picture from AVO, Photograph by Brandon Wilson). The last eruption from Pavlof was in 2007.




Google Earth snapshot of Pavlof and Pavlof Sister volcanoes.
The Smithsonian GVP characterizes the volcano of being capable of Strombolian eruptions, and explosive eruptions. This eruption currently appears to be mostly effusive, or possibly Strombolian, although it's a bit unlikely that we'll get to see any great nighttime shots.

Pavlof joins Cleveland Volcano in the 'currently erupting' club of Alaskan stratovolcanoes, as earlier this month, Cleveland let out a nice explosion that was strong enough for air traffic to be diverted around the volcano (aside from this minor annoyance, that's pretty typical of Cleveland).

There are no major human populations immediately near Pavlof, although the town of Aleutian East Burrough with a population of around 2700+ lies about 12 miles SSW of the volcano. Damage to this area is unlikely, although if the volcano does have an ash eruption, ash fall could affect the area.

*****UPDATE 5/29*****
AVO has lowered Pavlof to alert level Yellow (Advisory) after a few days of inactivity and lower seismic readings. AVO's statement reads:

"Over the past three days, the eruptive activity at Pavlof have greatly declined. Seismic tremor and small discrete explosions are no longer detected in seismic and pressure sensor data. Satellite observations show no evidence of elevated surface temperatures, volcanic gas or ash emissions. There have been no visual observations from pilots or web cameras of any eruptive activity. Consequently, the Aviation Color Code was reduced to Yellow and the Volcano Alert Level to Advisory today (28 May) at 12:50 AKDT (20:50 UTC)."

It is still possible for the volcano to continue its eruption. Past eruptions have had periods of intense explosion, followed by lulls in activity.

*****UPDATE 6/10*****

Activity has resumed at Pavlof. The following statement from AVO details the continuing eruption:

"Ash emissions have resumed at Pavlof starting at approximately 11:00 AKDT (19:00 UTC) this morning as seen in satellite data and observed by pilots. Weak seismicity beginning at 10:57 AKDT accompanied the emissions and is ongoing."

and:

"Ash emissions from Pavlof continue. Seismic tremor and explosion signals accompany the activity. Persistent elevated surface temperatures consistent with lava effusion were observed over the past day in satellite images. Satellite images from the last day also show an ash plume extending 12 miles (20 km) southeast of the volcano. This direction is consistent with low-level (less than 20,000 ft asl) winds."

So it appears that the volcano may erupt in 'spurts' and will likely continue erupting for some time. If anything changes I'll post about it!



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